1. Field of the Invention
The present invention relates to a driving support device for alerting a driver when an object, e.g., another vehicle is approaching so as to cross a travel path of an own vehicle.
2. Description of the Related Art
Hitherto, as proposed in Japanese Patent No. 4992643, there is a known collision prevention device for sending, at an intersection between a priority road and a non-priority road, an alert from a priority vehicle to a non-priority vehicle when the vehicle (priority vehicle) traveling on the priority road is entering the intersection, and the vehicle (non-priority vehicle) also entering the intersection from the non-priority road is detected. This device is configured to evaluate a degree of danger of collision between the priority vehicle and the non-priority vehicle, and increase an intensity of the alert as the danger increases.
The above-mentioned device is configured to alert a driver of the non-priority vehicle, for example, by sounding an alert from the priority vehicle to the non-priority vehicle. On the other hand, a driving support device is conceivable, which is configured to alert the driver of the own vehicle irrespective of whether the own vehicle is the priority vehicle or the non-priority vehicle when another vehicle is approaching so as to cross a travel path toward which the own vehicle is heading.
The driver is preferably alerted at a timing suitable for the feeling of the driver. A timing that is too early annoys the driver. Conversely, a timing that is too late prevents the original function from being fulfilled (a collision avoidance operation cannot be carried out in time). Thus, for example, it is conceivable to calculate an estimated period (referred to as margin period) until the another vehicle reaches a position at which the another vehicle crosses the travel path of the own vehicle, and the driver is alerted at a timing when the margin period becomes equal to or less than a threshold.
However, when the alert timing is determined by using the margin period, for example, in a case where the another vehicle is traveling at a low speed, the another vehicle is considerably close to the own vehicle when the driver is actually alerted. In this case, the driver feels that the timing for the alert is late.